Did concussions play role in Lou Gehrig's disease?

With his head bowed and a barely detectable quiver in his voice, the baseball player known as the "Iron Horse" devastated the crowd at Yankee Stadium, not by hitting a home run, but by announcing that he was dying.
It was July 4, 1939, and Lou Gehrig, a first baseman for the New York Yankees, had reached the end of a storied career.

"Fans, for the past two weeks you have been reading about a bad break I got," said Gehrig, who during his career played 2,130 consecutive games and still holds the record for the most grand slams. "Yet today I consider myself the luckiest man on the face of the Earth."

Gehrig's words were chilling considering his diagnosis: amyotrophic lateral sclerosis. ALS is a rare, incurable neurodegenerative disease (eventually named after him) that first manifests as muscle weakness and quickly descends to paralysis, an inability to breathe and death.
More than 70 years after his speech, a new, small study in the Journal of Neuropathology and Experimental Neurology may have unlocked a tantalizing clue about Gehrig's illness -- one that could be connected to his history of concussions.

"He did have three or four major concussions that landed him in the hospital," said Dr. Ann McKee, associate professor of Neurology and Pathology at the Boston University School of Medicine. "It is interesting to speculate that they may have contributed to his ALS."...